Just to let you know that I extended the Peaberry firmware with a iambic keyer and a standalone transmit mode. I also wrote an accompanying HDSDR ExtIO plugin to work with the new firmware. Together, the two allow for a smooth CW keying with zero latency from key down to sidetone and RF signal.

Please note that the HW modifications are not necessary, and only an audio amp is needed to be connected to pin P1[4] to get the side tone, if you want to use the internal keyer. With straight key configuration (or with an external keyer), no hardware modification is needed.

Newly the firmware and HDSDR plugin offer amplifier timing configuration for semi-QSK and to avoid hot switching of the AMP relay.